The present disclosure relates to methods and apparatuses for controlling aircraft devices, such as flight control surfaces, with multiple actuators, such as a combination of electric and hydraulic actuators.
Existing commercial aircraft have a variety of flight control surfaces operated by redundant actuation systems. These redundant actuation systems may use hydraulically powered (or hydraulic) actuators, electrically powered (or electric) actuators or a combination thereof. Many current commercial aircraft use hydraulic actuators coupled to the aircraft rudder, elevators, ailerons, and other flight control devices. Electromechanical types of electric actuators (in which an electric motor drives a surface through a ball screw arrangement) are being used extensively on unpiloted vehicles, where the potential of a flight control surface jam is not a significant safety issue. Electrohydrostatic actuators or Integrated Actuator Packages (in which an electric motor drives a local hydraulic pump to provide hydraulic fluid flow to an actuator coupled to the flight control surface) have been flight tested and are being proposed for future aircraft. In one variation, known as an electrohydrostatic backup actuator, the actuator acts as a hydraulic actuator during normal operation (at which time it is powered by a central hydraulic system through a selector valve), but acts as an electrohydrostatic actuator in case the hydraulic system fails (at which time it is connected to an electric motor to pump hydraulic fluid through the same selector valve). While the foregoing actuators can provide requisite redundancies, there is a continual effort in the aircraft industry to further reduce component cost and weight to make the aircraft more cost effective to operate.
The following disclosure describes methods and apparatuses for controlling aircraft devices with multiple actuators. An apparatus for controlling an aircraft system having at least one moveable component can include, in one aspect of the invention, a first power system having a first probability of failure, a second power system having a second probability of failure greater than the first, and a first actuator coupled to the first power system, the first actuator being coupleable to the at least one moveable component. The first actuator can be configured to apply a first force to the at least one moveable component. The apparatus can further include a second actuator coupled to the second power system and can be operatively coupled to the first actuator and coupleable to the at least one moveable component. The second actuator can be configured to apply a second force to the at least one moveable component, with the second force being less than the first force.
In another aspect of the invention, the first and second actuators can simultaneously act on the moveable component. The first power system can have a probability of failure of about 10xe2x88x927 or less, and the second power system can have a probability of failure of about 10xe2x88x925. The first actuator can include an electrically driven motor coupled to a hydraulic pump, and the second actuator can include a valve coupleable to a supply of hydraulic fluid pressurized by an aircraft engine.
A method for manufacturing an aircraft system having at least one moveable component can include, in a further aspect of the invention, coupling a first actuator to the at least one moveable component and to a first power system having a first probability of failure. The first actuator can be configured to apply a first force to the at least one moveable component. The method can further include operatively coupling a second actuator to the first actuator, the at least one moveable component, and a second power system having a second probability of failure greater than the first probability of failure. The second actuator can be configured to apply a second force to the at least one moveable component, with the second force being less than the first force.
A method for operating an aircraft system having at least one moveable component can include, in another aspect of the invention, applying a first force to the at least one moveable component via a first actuator coupled to a first power system having a first probability of failure, and applying a second force to the at least one moveable component via a second actuator coupled to a second power system having a second probability of failure greater than the first probability of failure. The second force can be applied simultaneously with the first force and can be less than the first force. If the first actuator fails, the method can further include applying only the second force to the at least one moveable component.